Veolia is preparing the energy by-product of coal combustion at Elektrárna-Třebovice for reuse in the production of industrial abrasive materials.
Electricity in the Czech Republic is still largely produced in coal-fired power plants. Coal is burned in a boiler, the heat generated heats water, which is turned into steam that drives a turbine that generates electricity. This classic electricity generation process is still used in many countries. What is new, however, is that it applies the principles of the circular economy. How is this possible?
The combustion of coal produces a molten slag in the combustion chamber of bottom-fired boilers. This is a mixture of aluminium oxide that is the product of burning coal at high temperatures. Thermal power plants do not usually process the slag, so it accumulates in landfills.
However, it is a by-product that can be used! At the Ostrava-Třebovice power plant, Veolia produces almost 10,000 tonnes of slag annually and ensures its reuse.
Blasting and balotining
How does it work? The molten slag is removed from the boiler and soaked in a water bath. There it crystallises into glassy granules, which are then finely ground. After processing, the slag has an ideal hardness and density, so that it can be used as a substitute for natural materials used in blasting or in balotining.
These two techniques are used in surface preparation - abrasive materials are thrown against the surface to be machined by high velocity compressed air. Microscopic granules are used to clean and smooth the surface as well as remove any deposits on it. For example, old paint is removed from car bodies in this way.
Blasting or balotinating usually uses a mixture of sand and crystalline silica, a material that is very harmful to health if inhaled. Microscopic slag granules do not contain any harmful substances.
The use of slag for the production of microscopic granulate solves two problems at once: it reduces the volume of waste that thermal power plants in the Czech Republic dispose of by landfilling, and at the same time it is an effective and harmless substitute for industrial surface treatment. The circular economy has more than one ace up its sleeve for us!
More information at www.veolia.cz
